Monolithic Blue LED Series Arrays for High-Voltage AC Operation

Abstract

Design and fabrication of monolithic blue LED series arrays that can be operated under high ac voltage are described. Several LEDs, such as 3, 7, and 20, are connected in series and in parallel to meet ac operation. The chip size of a single device is 150 μm × 120 μm and the total size is 1.1 mm × 1 mm for a 40 (20 + 20) LED array. Deep dry etching was performed as device isolation. Two‐layer interconnection and air bridge are utilized to connect the devices in an array. The monolithic series array exhibit the expected operation function under dc and ac bias. The output power and forward voltage are almost proportional to LED numbers connected in series. On‐wafer measurement shows that the output power is 40 mW for 40 (20 + 20) LED array under ac 72 V.

Method to design alternating current light-emitting diodes luminous flux

“…In the process of packaging, uneven settlement of phosphor induce its non-uniform distribution, then light spot produced by LED is not uniform. AC LEDs are composed of many micro-LEDs, obviously uniformity among micro-LEDs influence performance of the whole AC LEDs, such as luminous uniformity and chromaticity uniformity (Ao et al 2002;Xu et al 2008). Uniformity of micro-LEDs was decided primarily by wafer and fabrication process, under constant electrical current if light output power and forward voltage are almost proportional to N number of LED connected in series, the uniformity of micro-LEDs is high.…”

“…Original arrangement called anti-parallel is composed of two LED series lighting in turn during positive and negative half cycle of AC (Ao et al 2002;Jiang et al 2005). Wheatstone bridge AC LED proposed by Jaehee, etc.…”

A Comparative Study of GaN‐Based Direct Current and Alternating Current High Voltage Light‐Emitting Diodes

“…Unlike DC‐HV LED, AC‐HV LED can directly work under AC without converter, thus reducing the cost of LED lighting systems, and avoiding more than 10% energy loss due to poor AC‐DC conversion efficiency. Wheatstone Bridge (WB) circuit is usually adopted in the AC‐HV LEDs to improve the device efficiency by increasing the radiation area in each bias direction . However, there is few works focusing on the direct comparison between DC‐HV LED and AC‐HV LED.…”

Numerical Study of Thermal Behavior in Alternating Current Light-Emitting Diodes

“…They then measured the temperature and the basic illumination characteristics of the array. Ao et al [6] successfully designed a blue 40-chip AC LED array powered by alternating current, which led to the development of chip-level semiconductor AC LEDs. A single device had a chip size of 150 m × 120 m while the LED array had a total size of 1.1 mm × 1 mm, and an output power of 40 mW under AC 72 volts.…”